Time-Resolved Spectroscopy of Bulk and Thin Film Structure and Dynamics

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9317198 Nelson Femtosecond through millisecond time-resolved spectroscopy of condensed matter will be conducted to understand the dynamics of structural change in solids and liquids. Structural phase transitions between crystalline phases and structural evolution in glass-forming liquids and polymers will be examined. The results will be analyzed in terms of theoretical models of structural change, which describe the behavior of whole classes of materials and which therefore transcend individual materials, and in terms of molecular models which attempt to explain the behavior of specihc materials by taking their distinguishing characteristics into account. Measurements of the mechanical and thermal conductivity properties of thin films will also be performed. The goals will be to understand the relations between the linear mechanical response of the interface, the nonlinear response (e.g. peeling) measured by destructive tests, and the interface chemistry and bonding. The work on thin film polymers will have an immediate practical impact. The proposed method permits noncontact, nondestructive, rapid in situ determination of mechanical and thermal properties (elastic and loss moduli, thermal diffusivities) of supported or unsupported polymer films used in microelectronics, protective coatings, and other applications. If noncontact adhesion quality assessment proves possible, this will present a truly revolutionary tool to the applied community. ***